Abstract
Introduction:
Risk factors for developmental dysplasia of the hip (DDH) in early infancy have never been validated from basic principles; their relevance remains controversial.
Purpose:
To determine risk factors for DDH using newly developed diagnostic criteria based on international consensus.
Methods:
In this population-based cohort study, 9904 babies born at a secondary care unit (2010–2012) received a standardised examination (usually within 24 hours postpartum) in which we prospectively ascertained the presence of the common risk factors for DDH (breech, family history, etc). Infants exhibiting ≥1 factor were eligible and underwent ultrasound testing within 8 weeks. Alpha angles were measured by surgeon/radiologist in consensus and blinded to risk factors and age. Using multivariable methods we evaluated the association of the risk factors and ultrasonographic DDH using criteria based on international consensus.
Results:
1766 (18%) newborns exhibited ≥1 risk factor for DDH. Of these 1489 (84%) infants participated. To date, 1296 (87%) completed the ultrasound at a mean age of 8±3 weeks. Of the 1296, 55 (4%) patients exhibited alpha <55° and 43 (3%) exhibited alpha <50°. Of all risk factors, only female gender was associated with an alpha <55° (RR=2; 95% CI=1.1, 3.5; p=.01). In contrast, abnormal clinical examination findings of the hip were strongly associated with DDH (p<.0001).
Conclusion:
In a prospective study using robust case definitions, commonly known risk factors were not clinically important markers of DDH when DDH was defined by consensus criteria. Given the generally poor and conflicting evidence on risk factors for DDH, our preliminary results suggest a new approach is needed in the risk prediction of DDH.
Level of evidence: I
